Portable scanning receivers.
PORTABLE SCANNING RECEIVERS.
Anatoly Anatolyevich Khorev, Candidate of Military Sciences
Source: «Special Equipment» magazine
Modern portable scanning receivers are widely used to solve radio reconnaissance and radio monitoring tasks, as well as to search for unauthorized means of intercepting information that use a radio channel to transmit information.
Scanning receivers can be divided into two groups: portable scanning receivers and transportable portable scanning receivers. Portable ones include small-sized scanning receivers weighing 150-350 g (IC-R1, IC-R10, DJ-X1 D, AR-1500, AR-2700, AR-8000, MVT-700, MVT-7100, MVT-7200, PR-1300A, HSC-050, etc.). They have independent battery power sources and can easily fit into an inside jacket pocket.
Despite their small size and weight, such receivers allow reconnaissance and control in the frequency range from 100-500 kHz to 1300 MHz, and some types of receivers — up to 1900 MHz (“AR-8000”) and even up to 2060 MHz (“HSC-050”).
They provide reception with amplitude (AM), narrow-band (NFM) and wide-band (WFM) frequency modulation. Receivers “AR-8000” and “HSC-050” in addition to the specified types receive signals with amplitude single-sideband modulation (SSB) in the upper sideband (USB) and lower sideband (LSB) reception mode, as well as telegraph signals (CW). In this case, the sensitivity of the receivers with a signal-to-noise ratio of 10 dB (relative to 1 μV) is: when receiving signals with NFM modulation — 0.35-1 μV, with WFM modulation — 1-6 μV. Selectivity at the level of minus 6 dB is 12-15 and 150-180 kHz respectively.
Portable scanning receivers have from 100 to 1000 memory channels and provide a scanning speed of 20 to 30 channels per second with a tuning step from 50-500 Hz to 50-1000 kHz. Some types of receivers, such as AR-2700, AR-8000, IC-R10 can be controlled by a computer.
Transportable scanning receivers (IC-R100, AR-3030, AR-3000A, AR-5000, IC-R72, IC-R7100, IC-R8500, IC-R9000, AX-700B, EB-100, etc.) differ from portable ones by their slightly greater weight from 1.2 to 6.8 kg, dimensions and, of course, greater capabilities. They are usually installed either indoors or in cars.
Almost all portable scanning receivers can be controlled from a PC.
The characteristics of some scanning receivers are shown in Table 1.
Scanning receivers (both portable and transportable) can operate in one of the following modes:
- automatic scanning mode in a given frequency range;
- automatic scanning mode by fixed frequencies;
- manual operating mode.
| First operating modereceiver is the main one when detecting the frequencies of operating electronic equipment (when solving radio reconnaissance and radio monitoring tasks), as well as when searching for radio bug emissions. In this mode, the initial and final scanning frequencies, the frequency tuning step and the modulation type are set.
As a rule, there are several programmable frequency ranges in which scanning is carried out. For example, for the AR-3000A there are four, for the IC-R1 — ten, and for the AR-8000 — twenty. Operational switching between the specified frequency ranges is carried out using the function keys. In this operating mode, it is possible to scan the range with skipping frequencies stored in memory channels specially allocated for this purpose. Such channels are often called masked. The frequency skipping function is enabled when setting the scanning mode and is used to reduce the range scanning time. In this case, the memory block usually records the frequencies of radio stations constantly operating in a given area, which are of no interest from the point of view of reconnaissance or control. For example, frequencies allocated for television and radio broadcasting stations. |
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Fig. 1. AR-3000A Stationary Scanning Receiver |
Several scanning modes can be used:
1. When a signal is detected (its level exceeds the set threshold), scanning stops and resumes when the operator presses the function key.
2. When a signal is detected, scanning stops and resumes after the signal disappears.
3. When an audio signal is detected, scanning stops and resumes after the signal disappears.
4. When a signal is detected, scanning stops for preliminary signal analysis by the operator and resumes after several seconds. For example, for the AX-700E receiver — after 5 seconds, and for the AR-3000A receiver this time can vary in the range from 0 to 9 seconds.
Some receivers have the ability to automatically record the frequencies of detected signals into memory during scanning. Recording into the memory channels allocated for these purposes is performed sequentially in the order in which signals are received. For example, the AR-8000 receiver has 50 channels in the “j” bank allocated for recording signals detected during scanning.
The operator can listen to the detected signals through headphones or a built-in loudspeaker. Selecting the desired type of detector (NFM, WFM, etc.) ensures optimal demodulation of the received signals.
Second operation modereceivers is used in radio reconnaissance and radio monitoring, if the possible frequencies of radio equipment are known and recorded in the memory channels.
For each memory channel, the frequency value, the type of modulation and, for some types of receivers, the attenuation of the input attenuator are entered.
The information stored in each memory cell (channel) can be easily called up on the liquid crystal display using the function keys.
Scanning of memory channels is performed sequentially, and, just as in the first operating mode, the possibility of scanning with skipping frequencies recorded in masked channels and the possibility of automatic recording of frequencies of detected signals into memory are provided.
Some receivers have a memory scanning mode for a given modulation type. In this case, all memory channels programmed for the selected modulation type are scanned. For example, if the AM modulation type is set in a memory channel, and the scanning is carried out according to the FM modulation type, then this channel is skipped during scanning.
As a rule, the zero channels of each memory block are priority ones, which allows for priority viewing.
The third operation modereceivers is used for detailed examination of the entire or several frequency ranges and differs from the first mode in that the receivers are retuned by the operator using the frequency change knob, while information about the tuning frequency, modulation type, input signal level, etc. is displayed on the liquid crystal display.
The frequency is retuned with the selected retuning step. For a faster frequency change, the bit-by-bit mode is used, in which the frequency changes sequentially by bits (for example: 100 MHz, 10 MHz, 1 MHz, 100 kHz, etc.). This operating mode allows you to quickly and easily reach the desired frequency range.
| A number of scanning receivers display the level of the received signal in addition to information about the receiver tuning frequency and the type of modulation. For example, the AR-3000A receivers display the input signal level as a 9-segment diagram. The following signal level approximation is used: 1 — 1.0 μV; 7 — 30.0 μV; 9 — 300.0 μV.
The signal spectrum can be analyzed using a special panoramic attachment SDU-5000. Scanning receivers are available in both standard design and as separate units connected to a PC, or as a printed circuit board inserted into a PC. Such receivers include scanning receivers IC-PCR1000 and Winradio. Receiver IC-PCR1000 is made as a separate unit and operates under PC control via a built-in computer interface RS-232C. |
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Fig. 2. IC-PCR1000 Receiver |
The scanner has a noise suppressor, an automatic frequency adjustment function, and an automatic stop scanning function on modulated signals. The kit includes special control software for Windows.
Main technical characteristics of the IC-PCR1000:
- operating frequency range: 0.01-1300 MHz;
- modification types of received signals: USB/LSB/CW and AM/FM/WFM;
- number of memory channels: unlimited, stored in frequency banks on the PC hard drive;
- minimum frequency resolution: 1 Hz;
- reception parameter setting mode when selecting a frequency: automatic.
The unit measures 127x30x199 mm and weighs 1 kg.
Universal scanning radio receiver Winradiois made in the form of an ISA IBM printed circuit board (dimensions: 294x121x20 mm). It operates under PC control. It has an automatic frequency scanning mode within the entire range of 500 kHz — 1300 MHz. The scanning speed is 50 channels/s. It carries out reception in WFM/NFM/AM/SSB modes. Sensitivity is 0.5 μV. It has an unlimited number of memory channels located in frequency banks on the PC hard disk. Allows you to display spectrograms and oscillograms of received signals on the PC display screen, provide data on the levels of input signals. The frequency tuning step can be set within the range from 1 kHz to 1 MHz. The control panel is displayed on the monitor screen.
To search for radio bugs, along with conventional scanning receivers, specially designed ones are also used, for example, Scanlock ECM Plus, “Scorpion” or MRA- 3.
The portable Scanlock ECM Plus system is a special radio receiver designed to detect, identify and locate bugs transmitting information via radio (in the frequency range from 10 kHz to 4 GHz), as well as via wire lines (in the frequency range from 8 kHz to 10 MHz), including the power grid, telephone cables (a special interface for connecting the device to a telephone line is included in the kit), intercom lines, fire alarms, etc.
With a signal-to-noise ratio of 10 dB, the receiver sensitivity in the range of 10 .. 1 100 MHz is — 85 dBm, in the range above 1 100 MHz —75 dBm, in the range below 10 MHz — 90 dBm.
The main advantage of Scanlock ECM Plus is the ability to quickly automatically reconfigure in a wide frequency range. Scanning over the range is performed automatically or manually. In the automatic scanning mode, reconfiguration can be performed in increments from 1 to 99 kHz. The duration of analysis of each discrete frequency in automatic mode is 0.7 sec. In manual mode, the reconfiguration step can be selected from the following values: 1, 2, 5, 10, 20, 50, 100 and 200 kHz.
The receiver has AM and FM detectors.
The device allows for accelerated automatic scanning of the “strongest” signals, thereby significantly reducing the time it takes to detect bug emissions. That is, when the scanning mode is turned on, the receiver captures the most powerful signal and analyzes it, then sequentially analyzes less “strong” signals.
Frequency measurement can be performed by simply pressing a button. The operator identifies the detected signal by analyzing its frequency and listening through headphones or a built-in speaker. Identification of the detected signal can also be performed by correlating the received signal with the test signal.
The complex is powered both by the built-in battery and by the 220/240 V network. The battery provides 8-hour operation of the receiver.
The overall dimensions of the receiver are 310x240x80 mm, and its weight is 6.3 kg. The receiver with accessories is placed in an attaché case. The total weight of the complex with the case is 15.2 kg.
The portable combination device “Scorpion” combines the functions of a conventional scanning receiver, radio frequency meter, interceptor and jammer.
Having good selectivity and sensitivity (not worse than 20 μV) in automatic mode, like any scanning receiver, it can view the frequency range from 30 to 2000 MHz with a bandwidth of 200 kHz. At the same time, the two-line 16-digit liquid crystal display (LCD) displays information about the frequency, input signal level and other operating modes of the device.
The receiver has AM and FM detectors and allows you to listen to received signals through the built-in speaker.
| The frequency measurement error is ± 10 kHz. The relative level of the received signal is displayed on a 16-segment indicator (measurement error ± 3 dB per segment). When measuring the level of powerful signals, an attenuator can be used, weakening the input signal to 50 dB.
The built-in memory unit allows you to remember and skip during scanning (“cut”) up to 128 frequencies of known signals (frequencies of radio and television stations, etc.), entered by the operator. When adjusting the receiver sensitivity using the input attenuator and excluding known signals from the frequency search, the scanning time of the entire range from 30 to 2000 MHz will not exceed 10 s. In this case, the device can be used for continuous radio monitoring with constant scanning of a given frequency range. A distinctive feature of the device is that, simultaneously with the functions of detecting bugs, it is also capable of suppressing them by setting up targeted interference. The output power of the interference transmitter is 50 mW in a frequency band of 200 kHz. The “Scorpion” device has small dimensions (166x90x29 mm without antenna) and weight. The device is powered by 8 AA batteries, the status of which is displayed on the LCD. |
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Fig. 3. “SCORPION” radio monitoring device |
The MRA-3 device is also specially designed to search for radio bugs in the frequency range from 42 to 2700 MHz and can be used for both periodic and constant (continuous) radio monitoring of premises.
It has a sensitivity of 20 — 60 μV in the frequency range from 50 to 1200 MHz and 60 — 1000 μV in the ranges of 42 — 50 MHz and 1200 — 2700 MHz. The intermediate frequency (IF) bandwidth is 400 kHz.
The device allows detecting signals with amplitude (AM) and frequency (WFM, NFM) modulation and measuring their relative level, which is reflected on a 40-bit linear indicator.
The device has 512 channels of “long-term” memory and 16 rewritable channels for recording and subsequent analysis of “new” signals detected during scanning. The device has protection against unauthorized access to spectral memory channels.
For the initial recording of the frequency spectrum, the receiver scans the operating range four times in a row for 24 seconds (the scanning time of the spectral range is 6 seconds). The operator has the opportunity to analyze the signals recorded in the memory. Subsequently, the receiver is switched to automatic operation mode. During each scan, a comparison is made between the signals detected and those recorded in the “long-term” memory. When a new signal is detected, an alarm is triggered, and this signal is recorded in the memory block of new signals for subsequent verification. After analyzing new signals, they can be written to the spectral memory in the spectrum update mode (adding new signals).
The MRA-3 device has dimensions of 136x49x137 and weighs 620 g (including the battery).
Table 1.
Main characteristics of portable scanning receivers